Nonspecific
hypothalamic hormones such as
thyrotropin-releasing hormone or
luteinizing hormone-releasing hormone, or both, elicited abnormal
growth hormone responses in 73 of 108 (67.6%) acromegalic patients. After transsphenoidal adenomectomy, the provocative tests using these
hormones were repeated in 26 patients with abnormal preoperative
growth hormone responses to study variations in these responses during a 1-8-year observation period (average duration, 4 years). After surgery, 7 of the 26 patients regained normal basal
growth hormone levels (less than 5 ng/mL) and manifested normal responses to the
hypothalamic hormones. During the postoperative observation period, their basal
growth hormone levels remained normal as did their responses to provocation with
hypothalamic hormones, confirming that the
adenoma had been completely resected. Eight other patients demonstrated normal
growth hormone levels after surgery; however, they continued to have abnormal responses to provocation with
hypothalamic hormones, suggesting the presence of residual adenomatous tissue in the gland. These patients manifested no marked increase in basal or peak
growth hormone levels during the follow-up period (from less than 1 to less than 7.5 years) and they were all in clinical remission without any other treatment. Only one incompletely adenomectomized patient who had received no additional treatment experienced regrowth of the
tumor. The main factor affecting the surgical results appears to be the preoperative basal
growth hormone level, because abnormal
growth hormone secretion ceased in all patients who had manifested preoperative levels below 45 ng/mL. Technical refinements of the operative procedure are another important factor in the postoperative outcome. Peritumoral tissue resection after simple selective adenomectomy is mandatory for better surgical results. Our studies indicate that fairly good results can be obtained without risk of the recurrence of the
tumor or regrowth, when postoperative
growth hormone levels are below 5 ng/mL and that the results are not affected by the postoperative
growth hormone responses to provocation with
hypothalamic hormones.